At present, main equipment for firing clay products like bricks and tiles etc are annular kilns and tunnel kilns. An annular kiln has lower heat efficiency, a bad working environment, heavy labor intensity and is in major part of manual operation. Therefore, besides some small brickfields which are employing annular kilns, most of the large and medium-sized brickfields adopt tunnel kilns. An existing tunnel kiln has a tunnel-typed kiln body, its bottom consists of a plurality of kiln cars, while the kiln cars with green bricks set on enter one end of the kiln body, pass through the kiln with four zones of preheating, firing, soaking, and cooling, come out from another end of the kiln body. Car pusher, transfer car and drafter etc should be provided. And a number of auxiliary railways should be paved for returning the cars to the kiln entry. Consequently existing tunnel kilns require pretty large investment, of which one third is for cars. In addition, since the cars has a higher daily maintenance cost for running under a high temperature environment, and air leakage on cars bottom results in quite an amount of heat loss.